[GRASS-user] i.pca gives error

GRASS GRASS user
1

Hi list,

i am processing plenty of modis subsets into a group called “pca”

when using WinGRASS it gives an error

GRASS 7.0.svn> i.pca --overwrite input=pca output_prefix=_msub
Computing covariance matrix…
100%
ERROR: No non-null values
GRASS 7.0.svn>

can anybody help please?

Martin

2

On Fri, Apr 4, 2014 at 1:47 PM, Martin van Brakel
<m.l.vanbrakel@gmail.com> wrote:

Hi list,

i am processing plenty of modis subsets into a group called "pca"

when using WinGRASS it gives an error

GRASS 7.0.svn> i.pca --overwrite input=pca output_prefix=_msub
Computing covariance matrix...
100%
ERROR: No non-null values
GRASS 7.0.svn>

Did you set the computational region to the map beforehand?

g.region rast=pca -p

then
i.pca ...

See also:
http://grasswiki.osgeo.org/wiki/Computational_region
Since we currently have issues on the server (slow), see also the wiki
mirror at:
http://grass.fsv.cvut.cz/wiki-mirror/index.php/Computational_region

hope this helps
Markus

3

that helps but it breaks there…

GRASS 7.0.svn> i.pca --overwrite input=pca output_prefix=_msub
Computing covariance matrix…
100%
Calculating principal components…
100%
Rescaling to range 0,255…
100%
Eigen values, (vectors), and [percent importance]:
GRASS 7.0.svn>

···

On Fri, Apr 4, 2014 at 5:44 PM, Markus Neteler <neteler@osgeo.org> wrote:

On Fri, Apr 4, 2014 at 1:47 PM, Martin van Brakel
<m.l.vanbrakel@gmail.com> wrote:

Hi list,

i am processing plenty of modis subsets into a group called “pca”

when using WinGRASS it gives an error

GRASS 7.0.svn> i.pca --overwrite input=pca output_prefix=_msub
Computing covariance matrix…
100%
ERROR: No non-null values
GRASS 7.0.svn>

Did you set the computational region to the map beforehand?

g.region rast=pca -p

then
i.pca …

See also:
http://grasswiki.osgeo.org/wiki/Computational_region
Since we currently have issues on the server (slow), see also the wiki
mirror at:
http://grass.fsv.cvut.cz/wiki-mirror/index.php/Computational_region

hope this helps
Markus

4

On Fri, Apr 4, 2014 at 2:43 PM, Martin van Brakel
<m.l.vanbrakel@gmail.com> wrote:

that helps but it breaks there...

GRASS 7.0.svn> i.pca --overwrite input=pca output_prefix=_msub
Computing covariance matrix...
100%
Calculating principal components...
100%
Rescaling to range 0,255...
100%
Eigen values, (vectors), and [percent importance]:
GRASS 7.0.svn>

Please try (just for fun) to not use the leading "_" in the prefix parameter.

Please also post the output of

g.version -g

Markus

5

The problem appeared to be the extent and the pixel resolution, g.region rast=file solved it, thanks

Martin

···

On Fri, Apr 4, 2014 at 6:17 PM, Markus Neteler <neteler@osgeo.org> wrote:

On Fri, Apr 4, 2014 at 2:43 PM, Martin van Brakel
<m.l.vanbrakel@gmail.com> wrote:

that helps but it breaks there…

GRASS 7.0.svn> i.pca --overwrite input=pca output_prefix=_msub
Computing covariance matrix…
100%
Calculating principal components…
100%
Rescaling to range 0,255…
100%
Eigen values, (vectors), and [percent importance]:
GRASS 7.0.svn>

Please try (just for fun) to not use the leading “_” in the prefix parameter.

Please also post the output of

g.version -g

Markus